[Milsurplus] Insulated Gate Bipolar Transistors

[David Stinson]

Well, now hold on a sec....
The whole idea of these is that the Gate circuit is extremely hi-Z
relative to the Collector/Emitter circuit.  In the "ideal" device,
the two circuits are completely isolated from each other.
All of the Gates go to a pull-down resistor to ground.
According to the specs,  with the gate swinging 
it's absolute maximum of +/- 20 volts,
the leakage current to the C/E circuit is about 100 nanoamps-
pretty tiny.  So if my pull-down is, say, a few K ohms,
we've got a voltage divider of a few bizillion ohms C/E to G,
with an itty-bitty fraction from G to ground, so even if
the compound device should see the whole B+ at zero mod,
it should never develop more than a few volts G to ground.
I'd probably have to drive it harder, but that's no problem.
I'm going to build a three-step device and do some 
DC measurements.... not ready to give up just yet ;-).
73 Dave S.